This application is related to copending application Ser. No. 297,608 filed Aug. 21, 1981 entitled "Step-up Inverter" and assigned to the same assignee as the present invention.
This invention relates to power conditioners and more particularly to dc to dc choppers and dc to ac converters.
Conventional three phase motor drive dc to ac inverters are limited to a maximum value of line-to-line motor voltage imposed by the value of the dc input voltage. This maximum output voltage corresponds to the well-known six step operation that occurs when pulse width modulation ceases. For a dc input voltage of E, the maximum line-to-line fundamental RMS voltage is 0.780E.In the past, if an extended output voltage range was desired, for example, to maintain constant volts per Hertz operation, a step-up transformer could be coupled to the output of an inverter with the inherent weight and volume disadvantages of the transformer.
It is an object of the present invention to provide an inverter that is capable of step-up and step-down operation.